alamb commented on code in PR #7168:
URL: https://github.com/apache/arrow-datafusion/pull/7168#discussion_r1280690763
##########
datafusion/core/src/dataframe.rs:
##########
@@ -151,20 +151,38 @@ impl DataFrame {
/// Expand each list element of a column to multiple rows.
///
+ /// Seee also:
+ ///
+ /// 1. [`UnnestOptions`] documentation for the behavior of `unnest`
+ /// 2. [`Self::unnest_column_with_options`]
+ ///
/// ```
/// # use datafusion::prelude::*;
/// # use datafusion::error::Result;
/// # #[tokio::main]
/// # async fn main() -> Result<()> {
/// let ctx = SessionContext::new();
/// let df = ctx.read_csv("tests/data/example.csv",
CsvReadOptions::new()).await?;
- /// let df = df.unnest_column("a")?;
+ /// let df = df.unnest_column_wtith_optons("a")?;
/// # Ok(())
/// # }
/// ```
pub fn unnest_column(self, column: &str) -> Result<DataFrame> {
+ self.unnest_column_with_options(column, UnnestOptions::new())
+ }
+
+ /// Expand each list element of a column to multiple rows, with
+ /// behavior controlled by [`UnnestOptions`].
+ ///
+ /// Please see the documentation on [`UnnestOptions`] for more
+ /// details about the meaning of unnest.
+ pub fn unnest_column_with_options(
Review Comment:
Here is the key -- add a `_with_options` variant and link to documentation
##########
datafusion/core/tests/dataframe/mod.rs:
##########
@@ -1044,6 +1044,82 @@ async fn unnest_columns() -> Result<()> {
Ok(())
}
+#[tokio::test]
+async fn unnest_column_preserve_nulls_not_supported() -> Result<()> {
+ // Unnest, preserving nulls not yet supported
+ let options = UnnestOptions::new().with_preserve_nulls(true);
+
+ let results = table_with_lists_and_nulls()
+ .await?
+ .clone()
+ .unnest_column_with_options("list", options)?
+ .collect()
+ .await;
+
+ assert_eq!(
+ results.unwrap_err().to_string(),
+ "This feature is not implemented: Unest with preserve_nulls=true"
Review Comment:
preserve_nulls is not yet supported, but here is a space for it
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